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Capacitor selection

  1. Feb 17, 2009 #1
    capacitor selection....


    I'm having a bit of trouble selecting a capacitor and I just want to know if anyones got any suggestions ?...

    I need a capacitor for decoupling...that would be suitable at 100kHz switching frequency..withstanding a current ripple of about 1A with a low ESR....this is required for decoupling. The circuit is supplied with 10V dc producing an output current of 50A.

    has anyone got any suggestions or specifications you have already worked with ?

    Last edited: Feb 18, 2009
  2. jcsd
  3. Feb 20, 2009 #2


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    Staff: Mentor

    Re: capacitor selection....

    If it's supplied with 10Vdc, why is there ripple current? Is this part of your synchronous Buck DC-DC circuit? Can you show us the schematic for the application of this capacitor -- that would help us help you understand your choices.
  4. Feb 20, 2009 #3
    Re: capacitor selection....


    I just drew this simple schematic now. It somewhat shows what the entire cct will look like..

    hope this helps...


    Attached Files:

  5. Feb 20, 2009 #4


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    Staff: Mentor

    Re: capacitor selection....

    What kind of capacitor options have you looked at so far? Why were you not happy with them? Tell us what work you have done in selecting this capacitor, other than just asking us about it.
  6. Feb 21, 2009 #5


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    Science Advisor
    Gold Member

    Re: capacitor selection....

    Berkeman, ANY decoupling capacitor will have ripple current. If it doesn't have ripple current then it doesn't need to be there.
    I believe the main thing you are looking for would be a low ESR/ESL cap. Grab a DigiKey catalog or go to the web-site. I believe they have selections for capacitors used specifically in switch mode power supplies.
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